Chromatographic membrane and chromatography test paper with micro-nano surface structure

Abstract

The present invention provides a chromatographic membrane and chromatographic test paper with a micro-nano surface structure. The surface structure of the chromatographic membrane of the present invention is composed of a series of symmetrical grooves arranged in parallel; the grooves are composed of continuous arrow-shaped triangles. The tail end of the arrow-shaped triangle is connected to the arrow end of the next arrow triangle through a straight microchannel, and there is an angle between the connection between the microchannel and the tail end of the arrow-shaped triangle, forming two wings of the arrow-shaped triangle. This micro-nano surface structure greatly enhances the capillary action, while preventing the liquid from flowing in a direction opposite to or tangential to the specified direction. Based on the replication and manufacturing of the surface micro-nano surface structure mold, this structure can be manufactured on the surface of plastic or metal foil, thereby mass-producing immunoassay chromatographic membranes with this structure. The chromatographic membrane can solve the dependence of existing chromatographic membranes on fiber materials, and solve the problems of low flow velocity, uniformity of flow performance and sample loss of existing chromatographic membranes.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical technology and more specifically relates to a chromatography membrane and a chromatography test paper with a micro-nano surface structure. Background Art

[0002] Chromatographic detection technology is one of the important detection technologies in the field of modern medical diagnosis. Its system usually consists of two phases: one phase is the mobile phase that carries and transports the target substance, and the other phase is the stationary phase used to screen and separate the target substance. Chromatographic technology can separate multiple mixed components in the mobile phase from the mobile phase and redistribute or fix them in the stationary phase, thereby providing a basis for qualitative and quantitative analysis of the substance. There are many types of chromatography technology, and the essential operating principles are basically the same; the more well-known ones include paper chromatography, column chromatography, thin layer chromatography, etc., which have been widely used in the biomedical field.

[0003] Driving the mobile phase to move through the stationary phase surface is an important basis for the implementation of chromatography technology. To achieve this goal, in traditional large-scale chromatography equipment (such as high-performance liquid chromatographs), slender hoses are combined with multiple groups of precision high-pressure pumps to form a fluid control system for the chromatography equipment. This chromatography technology achieved through mechanical movement can provide sufficient continuous delivery power for long-distance flowing sample fluids and can achieve detailed analysis of multiple mixed components; however, it relies on additional equipment and the slow movement speed of the mobile phase, making it difficult to carry out low-cost, portable applications for rapid analysis of small amounts of analytes.

[0004] In order to solve this problem, technical researchers have used the characteristics of capillary action that can pull the liquid to flow naturally to manufacture chromatographic membranes. The chromatographic membrane can be used without additional control equipment, and is portable and easy to use. Therefore, most chromatographic membranes currently use implementation schemes that use capillary action as the driving force for liquid flow. For example, most of the current methods use densely arranged fibers with a diameter of submillimeter or micrometer to construct chromatographic membranes, and the tiny gaps between the fibers constitute the capillary flow space inside the chromatographic membrane. The products of this chromatographic membrane include: nitrocellulose membrane, cellulose acetate membrane, nylon fiber membrane, polyester fiber membrane, etc., which can pull the liquid out of other stationary phases stacked on the surface of the chromatographic membrane and flow spontaneously under capillary action. However, the fiber gaps of this chromatographic membrane based on fiber are difficult to uniformly control, resulting in batch-to-batch and intra-batch differences in the liquid flow performance of the chromatographic membrane, and this difference is difficult to overcome; in addition, the flow speed of this capillary flow form is relatively slow, and there is no ability to limit the flow direction, which is not conducive to the rapid and directional flow of the liquid.

[0005] In recent years, technical researchers have paid more and more attention to the guiding and enhancing effects of surface structures on capillary flow, as well as their potential for application in the rapid and directional transport of liquids. In nature, studies have found that surface structures such as the lip of pitcher plants, the serrated leaves of Araucaria, the mandibles of ants, and the joints of spider silk not only have the ability to enhance capillary action, but also have special morphologies that can limit the direction of liquid flow. However, it is difficult to directly replicate such natural structures on the surface of artificial chromatographic membranes. On the one hand, the morphology of natural biological surfaces is diverse, such as the arched lip of pitcher plants, the rod-shaped extended Araucaria leaves, and the arc-shaped mandibles of ants. The practice of forcibly flattening the biological surface to directly replicate its structure will change its surface structural characteristics and make it lose its existing capillary characteristics. On the other hand, these natural surfaces usually have orderly, repeatedly stacked multi-layer three-dimensional morphologies, and there is a spatial distribution relationship between the layers of morphology, which is layer-by-layer inclusion and layer-by-layer overlap. These three-dimensional structures are difficult to directly replicate on artificial surfaces through industrialized embossing technology.

[0006] Therefore, in order to overcome the problems in existing artificial chromatographic membranes, it is urgent to develop and design a surface structure that can provide rapid directional flow of liquid based on the principle of spontaneous directional and continuous liquid transport of the above-mentioned surface structure and replicate it on an artificial surface to make a chromatographic membrane with this structure. This chromatographic membrane needs to have the ability of controllable flow orientation, excellent and uniform flow performance, and low liquid residue. The chromatographic membrane is expected to replace the existing filament-based chromatographic membrane and lay the foundation for a new generation of chromatography technology. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the above-mentioned problems, provide a chromatography membrane and chromatography test paper with a micro-nano surface structure, solve the problem of the existing chromatography membrane's dependence on fiber materials, and further solve the problems of uncontrollable flow orientation, slow flow, and insufficient flow uniformity of the existing chromatography membrane.

[0008] The purpose of the present invention is to provide a chromatography membrane with a micro-nano surface structure.

[0009] Another object of the present invention is to provide a method for preparing the chromatographic membrane.

[0010] Another object of the present invention is to provide a chromatography test paper with a micro-nano surface structure.

[0011] Another object of the present invention is to provide applications of the chromatography membrane and chromatography test paper.

[0012] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0013] The present invention designs a chromatographic membrane with a micro-nano surface structure that enables liquid to flow rapidly and directional. The surface of the chromatographic membrane has a micro-nano surface structure composed of a series of parallel symmetrical grooves; the grooves are composed of continuous arrow-shaped triangles, which are connected end to end through straight microchannels, and there is a sharp angle between the connection between the straight microchannel and the tail end of the arrow-shaped triangle The two wings of the arrow-shaped triangle are formed; the axial length of the arrow-shaped triangle is 5 to 10 times the cross-sectional width, and the cross-sectional width of the arrow-shaped triangle is controlled at the micrometer level, thereby constructing a narrow and long capillary flow space to significantly enhance the capillary effect; this enhanced capillary effect can pull the liquid to flow rapidly. Where γGS is the surface energy of the gas-solid interface, γSL is the surface energy of the solid-liquid interface, γGL is the surface energy of the gas-liquid interface, and θc is the limiting contact angle at which the liquid remains stable at the sharp angle boundary. It is designed based on surface wetting theory and surface tension analysis to play a role in limiting the flow direction of the fluid. It can be used to prevent the liquid from returning to the starting point of the flow and achieve rapid directional flow of the liquid.

[0014] The principle of this micro-nano surface structure guiding the rapid directional flow of liquid can be divided into two parts. After the liquid enters the narrow capillary flow space formed by the arrow-shaped triangle, the micrometer-scale flow channel greatly enhances the capillary effect, thereby driving the liquid to flow rapidly. At this time, the groove prevents the liquid from flowing in directions other than the axial direction, and the liquid flows in the direction of the tail end of the arrow-shaped triangle and the arrow direction at the same time.

[0015] 1) When flowing toward the tail end, the liquid reaches the sharp angle formed by the tail end of the arrow-shaped triangle and the microchannel and contacts the sharp angle; the strong shear stress provided by the sharp angle separates the liquid, forcing the liquid to move around quickly along both sides of the sharp angle; since there is less space on the two wings of the arrow-shaped triangle, most of the liquid flows into the straight microchannel connected to the arrow-shaped triangle after moving around, and under the enhanced capillary action, flows into the next arrow-shaped triangle space; and so on, the liquid continues to flow rapidly.

[0016] 2) When flowing in the direction of the arrow, the liquid follows capillary flow along the channel with a gradually decreasing width, enters the straight microchannel connected to the previous arrow-shaped triangular space, and reaches the sharp angle boundary formed by the straight microchannel and the tail end of the previous arrow-shaped triangular space. Due to the surface tension of the liquid, the sharp angle boundary here restricts the flow of the liquid. According to surface wetting theory and surface tension analysis, the liquid needs to continue to do volume work and increase the contact angle to a certain limit threshold before it can break through the sharp angle restriction and further flow into the previous arrow-shaped triangular space. Since the overall flow direction of the liquid is toward the tail end of the arrow-shaped triangle, the liquid contact angle at the sharp angle boundary will not be able to reach the limit threshold through volume work, thus achieving flow behavior control that restricts the directional flow of the liquid.

[0017] The chromatographic membrane with a micro-nano surface structure prepared by the present invention has the following flow behavior control capabilities with the help of the capillary action enhanced by the micro-nano surface structure: 1) It has the ability to quickly flow the liquid; 2) Due to the fluidity and continuity of the liquid, the chromatographic membrane can pull the liquid from other stationary phases stacked on the membrane surface to the micro-nano surface structure on the chromatographic membrane surface through capillary action; 3) With the help of the special morphology of the micro-nano surface structure, the chromatographic membrane has the ability to lock the liquid on the membrane, preventing the liquid from flowing in other directions opposite to or tangential to the specified flow direction, thereby achieving directional flow of the liquid. The flow behavior control of the chromatographic membrane can prevent the ineffective diffusion and overflow of the liquid on the chromatographic membrane; at the same time, it prevents the liquid from flowing back to the direction of the flow starting point of these water-absorbing media, thereby reducing the flow loss of the liquid. On the other hand, the hydrophilic and functionalized treatments of the chromatographic membrane after molding can prevent the non-specific adsorption of substances caused by hydrophobic effects, thereby reducing the flow loss of substances carried in the liquid on the basis of the above-mentioned beneficial effects.

[0018] The principle of the micro-nano surface structure provided by the present invention to guide the rapid directional flow of liquid is divided into two parts. The first part is that after the liquid enters the narrow capillary flow space formed by the arrow-shaped triangle, the micrometer-scale flow channel greatly enhances the capillary effect, thereby driving the liquid to flow rapidly. The second part is that the groove prevents the liquid from flowing in directions other than the axial direction, and the liquid flows in the direction of the tail end of the arrow-shaped triangle and the arrow direction at the same time.

[0019] Furthermore, the transverse length of the arrow-shaped triangle is 100 to 2000 μm; and the cross-sectional width of the arrow-shaped triangle is 20 to 400 μm.

[0020] Furthermore, the length of the microchannel is approximately 0.5 to 0.6 times the axial length L1 of the arrow-shaped triangle.

[0021] Furthermore, the minimum spacing between the grooves is approximately 0.5 to 0.6 times the width of the arrow-shaped triangular cross section.

[0022] Furthermore, the sharp angle The design value of is deduced based on surface wetting theory and surface tension analysis to meet Where γGS is the surface energy of the gas-solid interface, γSL is the surface energy of the solid-liquid interface, γGL is the surface energy of the gas-liquid interface, and θc is the limiting contact angle at which the liquid remains stable at a sharp angle boundary.

[0023] Furthermore, the sharp angle

[0024] Preferably, the chromatography membrane material provided by the present invention is a metal material, a plastic material, or a thermoplastic or thermosetting material.

[0025] More preferably, the metal material is one of aluminum profile, copper plate, iron plate or alloy plate; the plastic material is one of polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, polyurethane; the thermoplastic or thermosetting material is one of polydimethylsiloxane, polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, polyurethane, etc.

[0026] The present invention provides a method for preparing the chromatographic membrane, comprising the following steps:

[0027] S1. Manufacturing the micro-nano surface structure of claim 1 on the flat surface of a metal or plastic material by laser cutting, precision machining, photolithography or hot pressing to obtain a chromatography membrane having the micro-nano surface structure;

[0028] Or, the inverse structure of the micro-nano surface structure of claim 1 is manufactured on the flat surface of the material to obtain a manufacturing mold having the inverse structure of the micro-nano surface structure of claim 1; then, the solid phase film of the thermoplastic or thermosetting material is heated to the melting temperature, and the manufacturing mold of the inverse structure of the micro-nano surface structure is pressed onto the surface of the solid phase film, and the mold is kept printing on the solid phase film under a certain pressure for a period of time; after the printing is completed, the solid phase film and the mold are cooled, and the solid phase film and the mold are separated to obtain a chromatographic membrane having the micro-nano surface structure.

[0029] Preferably, the metal material is one of aluminum profiles, copper plates, iron plates or alloy plates.

[0030] Preferably, the plastic material is one of polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, and polyurethane.

[0031] Preferably, the thermoplastic or thermosetting material is one of polydimethylsiloxane, polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, polyurethane and the like.

[0032] Preferably, in step S1, the printing pressure is 1-300 kPa; and the printing time is 2-200 s.

[0033] Preferably, the hydrophilization and functionalization treatment method is a physical treatment method or a chemical treatment method.

[0034] More preferably, the physical treatment method includes laser oxidation and plasma treatment.

[0035] More preferably, the chemical treatment method includes hydrophilic coating treatment (using water-based acrylic polyurethane topcoat, silica coating), hydrophilic group modification (using Tween-20, polyethyleneimine) or sputtering evaporation treatment (using SiO 2 、TiO 2 、Al 2 O 3 ).

[0036] The invention provides application of the chromatography membrane in preparing chromatography test paper.

[0037] The invention provides a chromatography test paper with a micro-nano surface structure, comprising the chromatography membrane.

[0038] Furthermore, the chromatography test paper also includes other components of the chromatography test paper; such as an immunochromatography test paper including a supporting base plate, a conjugate pad, a water absorbent pad and a sample pad.

[0039] Furthermore, the chromatographic membrane is directly fixed on the surface of the supporting bottom plate, and a water absorbent pad and a binding pad are placed at both ends of the chromatographic membrane respectively; wherein the water absorbent pad and the binding pad partially overlap with the chromatographic membrane, and the rest are fixed to the surface of the supporting bottom plate; at the other end of the binding pad, a sample pad is placed, the sample pad partially overlaps with the binding pad, and the rest is fixed to the surface of the supporting bottom plate.

[0040] Furthermore, when the chromatographic membrane is used in a rapid immunoassay scenario, an immune binding region for capturing antigens or antibodies of protein molecules to be detected is provided on the surface of the chromatographic membrane; the immune binding region is formed by directly fixing the antigens or antibodies on the surface of the chromatographic membrane, or constructing an additional three-dimensional substrate on the surface of the chromatographic membrane.

[0041] The present invention provides an assembly of the immunochromatographic test paper: a chromatographic membrane is bonded and fixed on the surface of a sticky support base plate, and a water absorbent pad and a binding pad are respectively placed at both ends of the chromatographic membrane; wherein the water absorbent pad, the binding pad and the chromatographic membrane overlap by a length of 2 to 4 mm, and the remaining parts are bonded and fixed to the surface of the sticky support base plate; a sample pad is placed at the other end of the binding pad, the sample pad overlaps the binding pad by a length of 2 to 4 mm, and the remaining parts are bonded and fixed to the surface of the sticky support base plate.

[0042] Preferably, the width of the test paper is about 2.0-5.0 mm.

[0043] Preferably, the length of the sample pad is about 1.5-2.0 cm.

[0044] Preferably, the length of the binding pad is about 1.0-1.5 cm.

[0045] Preferably, the length of the chromatography membrane is about 2.0 to 5.0 cm.

[0046] Preferably, the length of the absorbent pad is about 1.5 to 2.5 cm.

[0047] The present invention provides applications of the chromatography test paper in liquid flow, chromatography, immune detection, nucleic acid detection and biological particle detection.

[0048] The present invention has the following beneficial effects:

[0049] The present invention provides a chromatographic membrane and a chromatographic test paper with a micro-nano surface structure. Through the special morphological structure design of the chromatographic membrane surface structure, the capillary effect is greatly enhanced, and at the same time, the liquid is prevented from flowing in a direction opposite to or tangential to the specified direction, thereby realizing the rapid directional flow of the liquid. This micro-nano surface structure can be replicated on a flat artificial surface, thereby obtaining a chromatographic membrane with rapid directional flow of liquid.

[0050] Compared with the existing chromatographic membranes based on fiber filaments, the chromatographic membrane provided by the present invention can solve the problem of the existing chromatographic membranes' dependence on fibrous filament materials, and further solve the problems of the existing chromatographic membranes' uncontrollable flow orientation, slow flow, and insufficient flow uniformity. Based on the replication and manufacturing of surface micro-nano surface structure molds, this structure can be manufactured on the surface of plastic or metal sheets, thereby mass-producing chromatographic membranes with this structure. Its implementation conditions are simpler and more uniform than the production and modification of existing chromatographic membranes, and the manufacturing process has good stability and reproducibility. Based on the above beneficial effects, the chromatographic membrane provided by the present invention has the application potential to replace existing chromatographic membranes, enhance the traction ability of chromatographic membranes on liquids, improve the problems of insufficient uniformity of flow performance and sample loss in current chromatographic membrane technology, and become a breakthrough for a new generation of chromatographic technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram and physical diagram of the micro-nano surface structure for rapid directional flow of liquid provided by the present invention;

[0052] Figure 2 A schematic diagram of the rapid directional flow of liquid on the micro-nano surface structure provided by the present invention;

[0053] Figure 3 This is a comparison result diagram of the chromatographic membrane of the present invention and the chromatographic membrane based on fiber in the directional flow of liquid in Comparative Example 1;

[0054] Figure 4 This is a comparison result of the chromatographic membrane of the present invention and the chromatographic membrane based on fiber in comparative example 2 in terms of rapid liquid flow;

[0055] Figure 5 This is a comparison result diagram of the liquid traction between the chromatographic membrane of the present invention and the chromatographic membrane based on fiber in Comparative Example 2;

[0056] Figure 6 A result diagram of the chromatography test strip with a micro-nano surface structure provided by the present invention for detecting the nucleocapsid protein of the new coronavirus (wherein, 1-sample pad, 2-labeled antibody binding pad, 3-chromatographic membrane with the micro-nano surface structure, 31-hydrophilic fiber layer embedded in the chromatography membrane (as an immune binding area), 4-water absorbent pad, 5-support base plate). DETAILED DESCRIPTION

[0057] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0058] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0059] Example 1 Design of Chromatographic Membrane with Micro-Nano Surface Structure

[0060] The present invention designs a micro-nano surface structure that can guide liquid to flow rapidly and directional. The micro-nano surface structure of the present invention is composed of a series of symmetrical grooves arranged in parallel, and the grooves are composed of continuous arrow-shaped triangles. The top view of the specific structure is as follows: Figure 1 As shown in a, each parallel symmetrical groove has the same shape and size, and the right side view of the cross section of the tail end of the arrow-shaped triangle is as follows Figure 1As shown in a. The width L2 of the tail section of the arrow-shaped triangle is controlled at the micrometer level, and the axial length L1 of the arrow is designed to be several times greater than the width L2 of the tail section of the arrow. Thus, a narrow capillary flow space is constructed to enhance the capillary effect and pull the liquid to flow quickly. The tail end of the arrow-shaped triangle is connected end to end by a short and narrow straight microchannel, and the connection between the straight microchannel and the arrow-shaped triangle forms a sharp angle, as shown in FIG. Figure 1 As shown in b, the straight microchannel and the tail end of the arrow form two wings of the arrow-shaped triangle. The sharp angle designed plays a role in limiting the flow direction of the fluid, which can be used to prevent the liquid from returning to the starting point of the flow and realize the rapid directional flow of the liquid. The actual picture of the micro-nano structure is shown in Figure 1 As shown in c.

[0061] Schematic diagram of rapid directional flow of liquid Figure 2 As shown in the figure, after the liquid enters the narrow capillary flow space formed by the arrow end of the arrow-shaped triangle, the micrometer-scale flow channel greatly enhances the capillary action, thereby driving the liquid to flow rapidly. At this time, the groove prevents the liquid from flowing in directions other than the axial direction, and the liquid simultaneously flows in the direction of the arrow of the arrow-shaped triangle toward the tail end.

[0062] The lateral length L1 of the arrow-shaped triangle designed by the present invention is 100 to 2000 μm; the cross-sectional width L2 of the tail end of the arrow-shaped triangle is 20 to 400 μm; the length of the straight microchannel connecting the arrow-shaped triangle from head to tail is about 0.5 to 0.6 times the lateral length L1 of the arrow-shaped triangle; the sharp angle formed between the two wings of the arrow-shaped triangle and the straight microchannel connecting the two arrow-shaped triangles is defined as Sharp angle The design value is deduced based on surface wetting theory and surface tension analysis to meet Among them, γGS is the surface energy of the gas-solid interface, γSL is the surface energy of the solid-liquid interface, γGL is the surface energy of the gas-liquid interface, and θc is the limit contact angle at which the liquid maintains stability at the sharp angle boundary, which plays a role in limiting the flow direction of the fluid and can be used to prevent the liquid from returning to the starting point of the flow, thereby achieving rapid directional flow of the liquid. Between the grooves formed by the continuous arrow-shaped triangles, the minimum spacing L3 of the grooves is about 0.5 to 0.6 times the width L2 of the cross section of the arrow-shaped triangle.

[0063] When the liquid flows toward the tail end, it reaches the sharp angle formed by the tail end of the arrow-shaped triangle and the microchannel and contacts the sharp angle; the strong shear stress provided by the sharp angle separates the liquid, forcing the liquid to move around rapidly along both sides of the sharp angle; since there is less space on the two wings of the arrow-shaped triangle, most of the liquid flows into the straight microchannel connected to the arrow-shaped triangle after moving around, and under the enhanced capillary action, flows into the next arrow-shaped triangle space; and so on, the liquid continues to flow rapidly.

[0064] When the liquid flows in the direction of the arrow, it follows capillary flow along the channel with a gradually decreasing width, enters the straight microchannel connected to the previous arrow-shaped triangular space, and reaches the sharp angle boundary formed by the straight microchannel and the tail end of the previous arrow-shaped triangular space. Due to the surface tension of the liquid, the sharp angle boundary here restricts the flow of the liquid. According to surface wetting theory and surface tension analysis, the liquid needs to continue to do volume work and increase the contact angle to a certain limit threshold before it can break through the sharp angle restriction and flow further into the previous arrow-shaped triangular space. Since the overall flow direction of the liquid is toward the tail end of the arrow-shaped triangle, the liquid contact angle at the sharp angle boundary will not be able to reach the limit threshold through volume work, thus achieving flow behavior control that restricts the directional flow of the liquid.

[0065] Example 2 Preparation of Chromatographic Membrane with Micro-Nano Surface Structure

[0066] S1, feeding the flat aluminum plate into the laser marking machine, and marking continuously for 2 cycles at a speed of 50 mm / s. The equipment is loaded with the drawings of the micro-nano surface structure, and the program controls the laser marking machine to construct the micro-nano surface structure on the surface of the flat aluminum plate, and obtains a chromatographic membrane with the micro-nano surface structure on the surface;

[0067] S2, cleaning the chromatographic membrane obtained in step S1, and performing hydrophilic and functional treatments. Specifically, using oxygen as a gas source, the chromatographic membrane is subjected to plasma treatment to obtain a hydrophilic micro-nano surface structure chromatographic membrane.

[0068] Example 3 Preparation of Chromatographic Membrane with Micro-Nano Surface Structure

[0069] S1, heating a flat polystyrene (PS) film to a melting temperature, and promptly pressing a mold for making the micro-nano surface structure onto the surface of the flat PS film, the heating temperature being 150° C.;

[0070] S2. Keep the mold printing on the PS film for 2 seconds, and the printing pressure does not exceed 30kPa;

[0071] S3. After printing, cool the PS film and the mold to room temperature;

[0072] S4. After the PS film recovers its hardness, the PS film and the mold are separated to obtain the chromatography membrane with the micro-nano surface structure on the surface.

[0073] S5, the chromatographic membrane is subjected to hydrophilic and functional treatment. Specifically, compressed air is first used as a gas source to perform plasma treatment on the novel chromatographic membrane with a biomimetic structure; then a polyethylene glycol aqueous solution is immediately added and heated for several hours; after being taken out, it is quickly rinsed with pure water to obtain a hydrophilic micro-nano surface structure chromatographic membrane.

[0074] Example 4 Preparation of Chromatographic Membrane with Micro-Nano Surface Structure

[0075] S1. Heat a flat polymethyl methacrylate (PMMA) film to a melting temperature, and promptly press a mold for making a micro-nano surface structure onto the surface of the flat PMMA film, the heating temperature being 165° C.;

[0076] S2. Keep the mold printing on the PMMA film for 2 seconds, and the printing pressure does not exceed 30 kPa;

[0077] S3. After printing, the PMMA film and the mold are cooled to room temperature;

[0078] S4, after the PMMA film recovers its hardness, the PMMA film and the mold are separated to obtain the chromatography membrane with the micro-nano surface structure on the surface;

[0079] S5, hydrophilizing and functionalizing the chromatographic membrane prepared in the above steps. Specifically, compressed air is first used as a gas source to perform plasma treatment on the chromatographic membrane; then, an acrylic polyurethane aqueous solution is immediately added and heated for several hours; after being taken out, it is quickly rinsed with pure water to obtain a hydrophilized micro-nano surface structure chromatographic membrane.

[0080] Example 5 Immunochromatographic Test Paper with Micro-Nano Surface Structure

[0081] The immunochromatographic test strip with a micro-nano surface structure provided in this embodiment includes a supporting base plate, a chromatographic membrane, a conjugation pad, a water-absorbing pad, and a sample pad; wherein the chromatographic membrane is prepared by using embodiments 2 to 4 of the present invention, and the supporting base plate, conjugation pad, water-absorbing pad, and sample pad, etc., can all be purchased commercially. The chromatographic membrane is directly fixed on the surface of the supporting base plate, and a water-absorbing pad and a conjugation pad are placed at both ends of the chromatographic membrane respectively; the water-absorbing pad and the conjugation pad partially overlap with the chromatographic membrane, and the rest is fixed to the surface of the supporting base plate; at the other end of the conjugation pad, a sample pad is placed, and the sample pad partially overlaps with the conjugation pad, and the rest is fixed to the surface of the supporting base plate.

[0082] Antigens or antibodies that capture the protein molecules to be tested are provided on the surface of the chromatographic membrane to form an immune binding area, which is used in rapid immunoassays.

[0083] The assembly method of the above-mentioned immunochromatographic test paper is as follows: the chromatographic membrane is bonded and fixed on the surface of the sticky support base plate, and a water-absorbing pad and a binding pad are placed at both ends of the chromatographic membrane respectively; the length of the water-absorbing pad, the binding pad and the chromatographic membrane overlapping is 2 to 4 mm, and the remaining part is bonded and fixed to the surface of the sticky support base plate; at the other end of the binding pad, a sample pad is placed, the length of the sample pad and the binding pad overlapping is 2 to 4 mm, and the remaining part is bonded and fixed to the surface of the sticky support base plate. Among them, the width of the test strip is about 2.0 to 5.0 mm, the length of the sample pad is about 1.5 to 2.0 cm, the length of the binding pad is about 1.0 to 1.5 cm, the length of the chromatographic membrane is about 2.0 to 5.0 cm, and the length of the water-absorbing pad is about 1.5 to 2.5 cm.

[0084] When using the immunochromatographic test paper, the sample solution needs to be added to the sample pad; after capillary flow, the sample solution fully penetrates the binding pad, releases the labeled antibody on the binding pad and combines with the sample to be tested in the sample solution; at the same time, the sample solution infiltrates the overlapping part of the binding pad and the chromatographic membrane. At this time, the micro-nano surface structure on the surface of the chromatographic membrane will pull the sample solution, release it from the binding pad, and continue to flow forward along the chromatographic membrane; during the liquid flow process, the sample solution fully contacts the immune binding area in the middle of the chromatographic membrane one by one to complete the immune reaction; finally, the sample solution reaches the end point of the flow, that is, the absorbent pad. Under the water absorption effect of the absorbent pad, all (or most) of the sample solutions carrying the test object will eventually flow through the immune binding area. At this point, the immunochromatographic reaction process ends. By interpreting the detection signal on the surface of the chromatographic membrane by various means, real-time detection results can be obtained.

[0085] Comparative Example 1

[0086] This comparative example provides a comparison of the liquid directional flow performance of the hydrophilized micro-nano surface structure chromatographic membrane prepared in Example 2 and the original fiber-based chromatographic membrane on the commonly used test paper products. 5 μL of pure water was added to both sides of the two chromatographic membranes, and the flow was observed while timing.

[0087] The comparison results of liquid directional flow are as follows Figure 3 As shown in the figure, a 5 μL pure water droplet is added to the end point of the flow of the hydrophilized micro-nano surface structure chromatographic membrane, and the pure water droplet cannot flow; after maintaining for 6 seconds, a 5 μL pure water droplet is added to the start point of the flow of the chromatographic membrane, and within 6 seconds, it can flow rapidly along the surface structure of the chromatographic membrane for a distance of more than 2 cm. In the above process (11s), the droplet added at the end point of the flow remains unable to flow, indicating that the chromatographic membrane has a role in restricting the flow direction of the droplet. The droplets added at both ends of the chromatographic membrane based on fiber filaments all show obvious flow behavior.

[0088] In summary, it is obvious that the chromatographic membrane provided by the present invention has the ability of directional flow of liquid that the chromatographic membrane based on fiber does not have.

[0089] Comparative Example 2

[0090] This comparative example provides a comparison of the performance of rapid liquid flow and traction liquid flow between the hydrophilized micro-nano surface structure chromatographic membrane prepared in Example 3 and the fiber-based chromatographic membrane originally installed on the test paper product. At the same time, 5 μL of red ink was added to the flow starting point of the two chromatographic membranes, and the rapid liquid flow performance was compared by observing the flow conditions. A glass fiber membrane was stacked at each of the flow starting points of the two membranes, and an equal volume of liquid was added to the two glass fiber membranes at the same time, and the flow conditions were observed to compare the traction liquid flow performance.

[0091] The comparison results of liquid fast flow performance are as follows Figure 4 As shown in the figure, within 3 seconds, the red ink droplet can flow 1 cm on the surface of the chromatographic membrane of the present invention; in contrast, the flow distance of the fiber-based chromatographic membrane in the same time is only about 2 / 3 of that of the chromatographic membrane.

[0092] The comparison results of the flow properties of traction liquids are as follows Figure 5 As shown in the figure, in the same time, the distance that the chromatography membrane releases and pulls the liquid flow from the stacked glass fiber membrane is significantly greater than that of the fiber-based chromatography membrane. In addition, the state of the residual red ink on the chromatography membrane after the chromatography is compared with the state of no liquid on the surface of the chromatography membrane before the chromatography begins, so as to compare the flow traction capacity of the chromatography membrane and the fiber-based chromatography membrane. As can be seen from the figure, the color difference of the red ink of the chromatography membrane before and after the chromatography is significantly smaller than that of the fiber-based chromatography membrane.

[0093] In summary, it is obvious that the chromatographic membrane provided by the present invention has the following advantages: 1) the liquid flow rate is significantly better than that of the chromatographic membrane based on fiber filaments; 2) it is easier to draw the liquid from the stationary phase stacked on the surface of the chromatographic membrane to the chromatographic membrane; 3) after the chromatography is completed, the amount of liquid remaining on the chromatographic membrane is less.

[0094] Example 6 Detection of novel coronavirus nucleocapsid protein

[0095] The chromatographic membrane prepared in Example 4 was used to prepare an immunochromatographic test strip for the detection of the new coronavirus nucleocapsid protein. The specific method is as follows:

[0096] 1. Coating of hydrophilic fiber layer:

[0097] In order to meet the needs of antigen-antibody binding, a hydrophilic three-dimensional substrate is added to the surface of the chromatographic membrane to increase the loading capacity of the capture antibody. The capture antibody is used to capture the new coronavirus nucleocapsid protein to be tested in the sample solution.

[0098] First, cellulose acetate powder is dissolved in dimethyl sulfoxide-acetone solution, and acrylic polyurethane is added as a hydrophilic additive to prepare a membrane-forming liquid; the membrane-forming liquid is coated on the surface of the hydrophilized micro-nano surface structure chromatography membrane prepared in Example 4, and then immediately immersed in water. At this time, the membrane-forming liquid containing cellulose acetate will quickly form on the surface of the hydrophilized micro-nano surface structure and be embedded in the micro-nano surface structure. At this point, a hydrophilic chromatography membrane with a hydrophilic fiber layer fixed on the surface micro-nano surface structure is obtained.

[0099] 2. Immobilization of nucleocapsid protein antibodies on chromatographic membranes:

[0100] Take 1-2 μL of cross-linking agent to soak the hydrophilic fiber layer of the hydrophilic chromatography membrane in step 1, and immediately add 1-2 μL of nucleocapsid protein antibody (purchased from Feipeng Biotechnology Co., Ltd.) and react at 37°C overnight to complete the process of cross-linking the hydrophilic fiber layer with the nucleocapsid protein antibody.

[0101] 3. The chromatographic membrane 3 solidified in the above step 2 is bonded and fixed on the surface of the adhesive support base plate 5, wherein the hydrophilic fiber layer 31 embedded in the chromatographic membrane is used as the immune binding area.

[0102] 4. On the surface of the supporting base plate 5 on which the chromatographic membrane is fixed, a water-absorbing pad 4 and a binding pad 2 on which the labeled antibody is fixed are placed at both ends of the chromatographic membrane 3, respectively; wherein, the overlapping length of the water-absorbing pad 4, the binding pad 2 and the chromatographic membrane 3 is 2-3 mm, and the remaining part is bonded and fixed to the surface of the sticky supporting base plate 5.

[0103] 4. Place the sample pad 1 at the other end of the conjugate pad. The overlap length of the sample pad 1 and the conjugate pad 2 is 2-3 mm, and the remaining portion is bonded and fixed to the surface of the adhesive support base plate 5.

[0104] 5. Detection of SARS-CoV-2 Nucleocapsid Protein

[0105] The nucleocapsid protein antibody is diluted to a working concentration in a buffer solution medium to prepare a simulated sample solution. The simulated sample solution is dripped onto the sample pad of the chromatography test paper, and the solution is waited for the chromatography flow to complete on the chromatography test paper, and the test result is read after 5 minutes.

[0106] Test results such as Figure 6 As shown, the test strip prepared by using the hydrophilized micro-nano surface structure chromatography membrane provided by the present invention can be used in chromatography detection and can provide correct positive results.

[0107] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A chromatography membrane having a micro-nano surface structure, characterized in that: The surface of the chromatographic membrane has a micro-nano surface structure composed of a series of parallel symmetrical grooves; the grooves are composed of continuous arrow-shaped triangles, which are connected end to end through straight microchannels, and there is a sharp angle φ between the connection between the straight microchannel and the tail end of the arrow-shaped triangle, forming two wings of the arrow-shaped triangle; The axial length of the arrow-shaped triangle is 5 to 10 times the cross-sectional width, and the cross-sectional width of the arrow-shaped triangle is controlled at a micrometer scale; The sharp angle φ≤π+arccos[(γGS-γSL) / γGL]-θc, wherein γGS is the surface energy of the gas-solid interface, γSL is the surface energy of the solid-liquid interface, γGL is the surface energy of the gas-liquid interface, and θc is the limit contact angle at which the liquid remains stable at the sharp angle boundary; the sharp angle φ is 10° to 20°; The axial length L1 of the arrow-shaped triangle of its micro-nano surface structure is 100 to 2000 μm; the cross-sectional width L2 of the arrow-shaped triangle is 20 to 400 μm; the length of the straight microchannel is 0.5 to 0.6 times the axial length L1 of the arrow-shaped triangle; and the minimum spacing L3 of each arrow-shaped triangular groove is 0.5 to 0.6 times the cross-sectional width L2 of the arrow-shaped triangle.

2. The method for preparing the chromatographic membrane according to claim 1, characterized in that: The following steps are involved: S1. Manufacturing the micro-nano surface structure of claim 1 on the flat surface of a metal or plastic material by laser cutting, precision machining, photolithography or hot pressing to obtain a chromatography membrane having the micro-nano surface structure; or manufacturing the inverse structure of the micro-nano surface structure of claim 1 on the flat surface of the material to obtain a manufacturing mold having the inverse structure of the micro-nano surface structure of claim 1; then heating the solid phase film of the thermoplastic or thermosetting material to the melting temperature, pressing the manufacturing mold of the inverse structure of the micro-nano surface structure onto the surface of the solid phase film, and keeping the mold printing on the solid phase film under a certain pressure for a period of time; After the printing is completed, the solid phase film and the mold are cooled, and the solid phase film and the mold are separated to obtain a chromatography membrane having the micro-nano surface structure; S2, subjecting the chromatographic membrane with the micro-nano surface structure obtained in step S1 to hydrophilic and functional treatment to obtain a chromatographic membrane with a hydrophilic micro-nano surface structure.

3. The method for preparing a chromatographic membrane according to claim 2, characterized in that: The metal material is one of aluminum profiles, copper plates, iron plates, and alloy plates; the plastic material is one of polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, and polyurethane.

4. The method for preparing a chromatographic membrane according to claim 2, characterized in that: The thermoplastic or thermosetting material is one of polydimethylsiloxane, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polyethylene, polyvinyl chloride, and polyurethane.

5. The method for preparing a chromatographic membrane according to claim 2, characterized in that: In step S1, the printing pressure is 1 to 300 kPa, and the printing time is 2 to 200 s.

6. Use of the chromatography membrane according to claim 1 in preparing chromatography test paper.

7. A chromatography test paper with a micro-nano surface structure, characterized in that: Comprising the chromatographic membrane according to claim 1.

8. The chromatography test paper according to claim 7, characterized in that: Also included are a support base, conjugate pad, absorbent pad, and sample pad.

9. Use of the chromatographic membrane according to claim 1 or the chromatographic test paper according to claim 7 or 8 in liquid flow, chromatography, immunoassay, nucleic acid detection, and biological particle detection.

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